Every October 31st, lazy and uninspired party goers flock to a different trendy costume!

Not too many years ago, every dude and his uncle dressed up like Heath Ledger's Joker! Back in the mid 1980s, we're sure Debbie Gibson & Yakov Smirnov costumes sold like hot cakes!! In 1804, we have it on good authority that all the hipsters dressed up like Aaron Burr for Halloween!

This year? Good luck finding a costume party that isn't filled with a half-dozen unimaginative souls dressed like Miley Cyrus at the VMAs, twerking their asses off to the Monster Mash!

Unfortunately for MileyBird, she is afforded no such luxury! She can't just show up to a party dressed as herself! They'd call her tacky! Or narcissistic! Or derivative!

So, while the world is dressed up like her this year, she'll be dressed up like… a donkey?

As we've told you, Mary Kate Olsen is a biiiiig horse lover - in fact, one of her horses even won first place at the 38th annual Hampton Classic Horse Show where she and her lovah Olivier Sarkozy were spotted canoodling in the stands.

Well, MK seemed to reallllllly be into the show, as she was all business in her black blazer and wearing a unique bun on her head. Is this the future of topknots??

Meanwhile, her beau was more interested in whispering sweet nothings in her ear while she watched all the horse action - could he be the true horse whisperer??

Ha!

Here's hoping we get to see Mary Kate ride some of them horses herself!